I haven't played the demo yet so these are my initial impressions just from reading the first post. I'll probably make a new post once I've completed the demo.
1. What are your thoughts about the game’s story and narrative?
This seems really cool! I wish I had more to say on that as feedback or something, but I can't think of anything to really critique here.
2. Do the main characters interest you?
If by the 'main characters' you mean just the playable ones, hate to say, but I find the NPCs a lot more interesting. That's not to say Ryota or Sophie seem dull: I just find characters like The Listener or the Whispering Shadow to be interesting because there's a lot of mystery surrounding them. I think Alexa seems cool for a similar reason.
3. How do you feel about the game’s artwork?
You did an awesome coloring job. I have massive issues with actually coloring my line-art without ruining it, so anyone who colors well has my admiration by default.
I can't answer 4 or 5 without having given it a play-through, so I'm going to start on the demo right now and get back to answer the rest